»What to say to someone who insists to pray«

When I told you "There is a dark book. If you read it, you will gain a piece of understanding but it will bring you closer to death and pain. It will result in slaughter, brutality and suffering"... then I am sure you would say, this is "kind of a satanic book".

Judging by the history of jews, christians and muslims, the study of their scriptures DOES INDEED result in slaughter.

this is non sequiter. its like saying that alexander the great reading about ancient wars is what caused him to kill so many people.